1. Field of the Invention
The present invention relates to a nozzle for continuous casting, and more particularly to a nozzle which is capable of uniformly supplying a required amount of gas to the inner wall surface thereof by providing a plurality of communication holes inside the nozzle body between the inner surface thereof and a gas pressure balance chamber disposed inside the nozzle body so as to communicate the chamber with the inner surface, the communication hole having a square measure corresponding to that of a circular hole having a diameter of 1.0 mm or less.
2. Description of the Prior Art
A gas blow-in type nozzle for continuous casting heretofore has been known wherein an inert gas is blown in to an inner surface of the nozzle through the nozzle body so as to form a gas seal on the inner wall surface and prevent the nozzle from clogging. As shown in FIGS. 1 and 2, this kind of nozzle has a gap which is made by using such solid material as will disappear during the burning process for manufacturing a nozzle, for example, paper, polypropyrene, nylon, paraffin, etc. Namely the gap is made by providing said material in an appropriate place inside the nozzle body at the time of molding and thereafter burning it down. The gap or gas pressure balance chamber 2 is connected via a gas inlet hole 3 to an inert gas supply source disposed outside the nozzle body 1 while being communicated to the inner surface of the nozzle body via open pores existing therein, whereby the inert gas is made to blow into the space between the inner wall surface and the molten steel. The open pores which communicate the gas pressure balance chamber 2 with the inner surface of the nozzle are naturally formed during the nozzle manufacturing process so that the existence of the open pores in not always uniform and varies according to the manufacturing conditions. Therefore there has arisen a problem that the amount of gas supplied to the inner surface is not constant or uniform. Especially in the case where the open pores of less than 5 .mu.m in diameter exist more than 50%, it is practically difficult to blow in the gas and impossible to form a perfect gas seal.